Acoustic characteristics of FeSe single crystals G. A. Zvyagina, T. N. Gaydamak, K. R. Zhekov, I. V. Bilich, V. D. Fil, D. A. Chareev and A. N. Vasiliev EPL, 101 5 (2013) 56005 Published online: 21 March 2013 DOI: 10.1209/0295-5075/101/56005